Apparatus for measurement of vertical obstructions

ABSTRACT

Accurate measurements of flight path obstructions are taken from a moving aerial platform. Platform position, including altitude, is combined with dynamic data including target distance and target elevation data to calculate obstruction height or altitude. An optical subsystem on the aerial platform images the obstructions and provides a video stream showing the obstructions. The video stream and aerial platform data are wirelessly communicated to a control terminal where an operator observes a presentation of obstructions and obstruction altitudes or heights. The operator can issue commands to the aerial platform.

TECHNICAL FIELD

Embodiments relate to the fields of aviation, mapping, and geospatialdata. In particular, embodiments relate to the creation and verificationof data relating to flight path obstructions.

BACKGROUND

One obvious requirement for aircraft safety is to avoid flying intothings. There are many possible flight path obstructions most of themhaving a specific and constant geographic coordinate and height.Obstruction coordinate and height data are contained in databases suchas the various geographic information system (GIS) databases used inflight planning and in producing navigation maps for pilots. Newobstructions are constantly being produced during and after constructionactivities and the quicker the new obstructions are added to thedatabases, the safer air travel is. Furthermore, obstruction locationand height should be occasionally verified to correct faulty GIS data.

Object height has been measured in a number of different ways. Forexample, aerial photograph stereography. In aerial photographstereography, two pictures are taken. After matching the featuresbetween the two pictures, stereographic equations are solved in anattempt to locate the features in a three dimensional space. To measureobstructions, one feature is the obstruction's top and another is theground at the obstructions base. The resolution suffers because aerialphotographs are taken in a direction which is orthogonal to themeasurement of interest. To wit, the camera is looking in theapproximately vertical axis, yet seeks to measure vertical size. Thismeans that small errors in the apparent position of vertical objects aremagnified geometrically. Also, fine structures such as antennae atoptowers or buildings are difficult to detect, yet an aircraft strikingone of these small antennae could be damaged or destroyed.

Down-looking LiDAR systems have been used to construct topographicdigital terrain maps. This at least makes a direct measure in thevertical, and indeed these systems provide excellent maps of largertopographic hazards to aviation including terrain and buildings.However, the detection of smaller features is a problem. LiDAR systemsmay be capable of measuring objects as small as a meter across, butcannot hope to measure an antenna of ½ inch diameter. As such, certaincommon aviation hazards are overlooked.

Perspective photographic measurement techniques use a picture ormultiple pictures taken with a camera instrumented to measure line ofsight angles. This method has the advantage of looking at themeasurement of interest—the obstruction from the side. However, inpractice it is not practical to image a building with enough pixelresolution to capture from the base of the building and be able toclearly measure the lightening rod on its top.

The existing methods do not provide for consistent and accuratemeasurement of the fine structure of obstructions. The fine structures,such as a ½ inch antenna, are quite capable of damaging aircraft.Systems and methods for rapidly, inexpensively, and accurately measuringobstruction heights are needed.

BRIEF SUMMARY

Aspects of the embodiments address limitations and flaws in the priorart by observing the fine structure of obstructions without the need toimage the entire obstruction.

It is therefore an aspect of the embodiments that an instrumentedaircraft locates and measures obstructions. The aircraft, perhaps anunmanned aerial vehicle (UAV), has a distance measuring module, analtitude measuring module, and an angle measuring module.

The distance measuring module measures the distance, the platformdistance, from the airborne platform to a target such as a flight pathobstruction. The altitude measuring module measures the airborneplatform's height or altitude. The angle measuring module measured anelevation angle indicating an angle between horizontal and a line fromthe aerial platform to the target.

It is another aspect of the embodiments that an analysis module acceptsthe platform distance, the platform altitude, and the elevation angle asinput and produces an estimate of the target's height as output.

It is a further aspect of the embodiments that a user, perhaps the UAV'sremote operator, observes the target height on a presentation module.The presentation module typically includes a video monitor displaying avideo stream captured by a camera in the UAV. The target height can beoverlayed onto the displayed video such that the user simultaneouslysees the target and an indication of the target's height.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying figures, in which like reference numerals refer toidentical or functionally similar elements throughout the separate viewsand which are incorporated in and form a part of the specification,further illustrate the present invention and, together with thebackground of the invention, brief summary of the invention, anddetailed description of the invention, serve to explain the principlesof the present invention.

FIG. 1 illustrates a ground station in communication with an airborneplatform in accordance with aspects of the embodiments;

FIG. 2 illustrates a system obtaining target height data in accordancewith aspects of the embodiments; and

FIG. 3 illustrates a target height measurement system communicating witha database in accordance with aspects of the embodiments.

DETAILED DESCRIPTION OF THE INVENTION

The particular values and configurations discussed in these non-limitingexamples can be varied and are cited merely to illustrate embodimentsand are not intended to limit the scope of the invention.

Accurate measurements of flight path obstructions are taken from amoving aerial platform. Platform position, including altitude, iscombined with dynamic data including target distance and targetelevation data to calculate obstruction height or altitude. An opticalsubsystem on the aerial platform images the obstructions and provides avideo stream showing the obstructions. The video stream and aerialplatform data are wirelessly communicated to a control terminal where anoperator observes a presentation of obstructions and obstructionaltitudes or heights. The operator can issue commands to the aerialplatform.

FIG. 1 illustrates a ground station 121 in communication with anairborne platform 120 in accordance with aspects of the embodiments. Auser 123 supplies control commands 118 into a user input module 122.Some of the control commands 118 command or control the ground station121 while others control the airborne platform 120. Ground stationcontrol commands can control the presentation of video and data by thepresentation module 101. Airborne platform control commands pass througha ground communications module 117 to a platform communications module103 within the airborne platform 120. Airborne platform control commandscan control heading, camera aim point, enable or disable onboardsystems, or other actions.

The airborne platform has a location module 115 that outputs theplatform location 116. For example, a Global Navigation Satellite System(GNSS) system such as the U.S. Global Positioning System (GPS) can beused to discern the airborne platform's geographic coordinates. A GPSreceiver can output the airborne platform location 116. A GNSS or GPSreceiver can also act as an altitude measuring module 105 by determiningand outputting the platform altitude 104. Other instruments, such as aradar altimeter, laser altimeter, or barometric altimeter can act as thealtitude measuring module 105.

An optics module 112 has optical, electro-optical, and mechanical-opticsubsystems for obtaining imaging and measuring elevation angle 108. Avideo module 110, such as a video camera, can produce a video stream 111that can be transmitted back to the ground station 121 and passed to asynthetic vision module 113. The synthetic vision module 113 can combinethe platform video stream 111 with other imagery or data overlays toproduce a presentation video stream 102 that is then displayed by thepresentation module 101 to the user 123.

The optics module 112 also contains an angle measuring module 109 thatproduces an elevation angle 108. The optics module can contain, but neednot contain, the distance measuring module 107 that measures theplatform distance 106. The platform distance 106 is the distance fromthe airborne platform 120 to a target. The angle measuring module can bea laser range finder (LRF), RADAR range finder, optical parallax rangefinder, or optical focus range finder. Many of these instruments areoptical and properly belong within the optics module 112. A differentway of measuring platform distance is through geographic coordinates.The target coordinates are often precisely known and contained within adatabase. The Euclidean distance between the platform location 116 andthe known target coordinates can be used as a platform distance 106.

The platform location 116, platform altitude 104, platform distance 106(or its analogs), and elevation angle 108 can be passed to an analysismodule 103 to produce a target height 119 that is then passed to thesynthetic vision module 113 for eventual display to the user 123. Theanalysis module 103 is illustrated as part of the ground station 121whereas many embodiments can contain it within the airborne platform 120as well. The calculation of target height from the measured data is amatter of applying high school level trigonometry.

FIG. 2 illustrates a system obtaining target height data in accordancewith aspects of the embodiments. A UAV 208 uses a GPS receiver todetermine platform location and altitude 214 above sea level. A laseraltimeter, on the other hand, would find the altitude above the ground215. A laser range finder 210 measures the platform distance 219 to atarget 216. A camera turret 211 contains a video camera 212 and an anglesensor 213. The camera turret 211 aims the video camera 212, andpreferentially the laser range finder 210, at the target 216. The videocamera 212 images the target 216 and an angle sensor 213 measures theelevation angle 217. The elevation angle is the angle between ahorizontal reference 218 and a line from the UAV 208 and the target 216.The camera turret 208 can be steered and controlled by a user issuingcommands to a ground station's 210 keyboard and mouse 202. The user canobserve a presentation video stream on a video monitor 203 displaying a3D synthetic presentation 204. The 3D synthetic presentation 204 canshow the camera video including a target image 205 as well as addedfeatures. The added features can include a target height annotation 207and a height scale reticule 206.

FIG. 3 illustrates a target height measurement system communicating witha database 302 in accordance with aspects of the embodiments. Thedatabase 302 contains obstruction coordinates 303. Each obstructioncoordinate can include obstruction latitude 304, obstruction longitude305, obstruction altitude 306, and obstruction height 307. Here,obstruction altitude is distance above sea level while obstructionheight is distance above the ground.

Obstruction data can be used to guide the airborne platform toward theobstruction. Navigation data 316 including the platform location(current position) and the obstruction coordinate (desired position) canbe passed to a navigation module 323 that then calculates a platformheading 324. The airborne platform 208 can then fly the platform heading324 to the target 314. Aiming data 319 is similar to navigation data 316with the exception that platform altitude 322 is helpful. It is alsohelpful if the obstruction coordinate 317 includes obstruction height307 or obstruction altitude 306. The aiming data 319 and the platformheading 324 are passed to an aiming module 325 that then determines anaiming vector 315 for the camera turret 211.

After finding the target 314, an operator can refine the aiming vectorto point at the top of the target 314. The platform location 318,platform altitude 322, platform distance, and elevation angle can thenbe passed to an analysis module that determines a target coordinate 308that can include target latitude 304, target longitude 305, targetaltitude 306, and target height 307. A database updating module 304 canthen update the database 302 when the target coordinate 308 is a moreaccurate measurement of the obstruction coordinates 303 than thatcurrently contained in the database 302.

Aircraft and other moving platforms are less stable than camera tripodsand, as such, a camera stabilization systems 328 can greatly smooth outthe acquired video stream and measurements. Furthermore, an aircraft isvery rarely always flying straight and level while also pointing exactlywhere it is going. An aircraft has a platform vector 327 that isindicative of the aircrafts attitude (pitch, yaw, and roll). A 3 axisinertial measurement systems (IMS) 326 are often used to measureplatform vectors 327. As such, the IMS can supply a horizontal referenceagainst which the elevation angle can be determined. Alternatively, theelevation angle can be easily calculated from the aiming vector and theplatform vector.

In certain embodiments, the optical subsystem is capable of variablemagnification (zoom) so that the operator can zoom in to examine finestructures on the obstruction such as antenna, lightening rods,flagpoles, cables and guy wires. A high resolution database can containentries for each of the fine structures on an obstruction. For example,a tall building can have entries for the building itself, its lighteningrod, and an antenna attached away from the lightening rod.

Another embodiment of the invention examines the full obstruction. Itcan work as follows. A mobile platform such as a UAV, aircraft, orground vehicle contains the requisite modules, such as GPS and opticsmodules, for measuring its own location as well as the relative locationof an aim point. The operator inputs a location on the surface of theearth at which the optical system is pointed. The operator then adjuststhe system until it points at the base of an obstruction. The operatorthen commands the computer to measure the distance to the obstructionbase from the optical system and the elevation angle to the base. Fromthis information a computer computes the location of the obstructionbase in three dimensions (e.g. latitude, longitude and altitude or othergeometric coordinate system).

Next, the operator scans the optical system up the obstruction to findthe highest point. The optical system must provide adequatemagnification to permit the operator to see fine structure objectsincluding cable, antennae and guy wires. The operator points the cameraat the top of the obstruction and again commands the computer to measurethe distance and the elevation angle. The computer uses this informationto compute the height of the obstruction. Note that the mobile platformcan take the bottom measurement from one platform location and the topmeasurement from a different platform location.

Details of Certain Embodiments

-   1. It is difficult to get an adequate LRF return signal from a small    antenna. In such a case, if the antenna is directly above the    obstruction base, the computer can be instructed to simply use the    obstruction base horizontal position to compute the distance to the    top of the obstruction.-   2. It is desirable that the optical camera system have an infrared    capability because of the presence of haze during typical    operations.-   3. High Definition video is preferable to standard definition video    because of the need to detect fine objects.-   4. A substantial optical magnification capability results in    improved fuel savings in the inspection aircraft.-   5. The software used to control the turret and record the data must    be designed for rapid efficient operation, allowing the verification    of the largest number of targets in the smallest amount of time.-   6. A criterion is given for the required proximity to an obstruction    for measurement purposes. It is a function of the smallest probable    obstruction size (say ½ inch), and the smallest object that can be    seen by the camera at a given range.-   7. The limitations of accuracy are primarily driven by the accuracy    of the measurements of the platform distance, elevation angle,    platform location and platform altitude.-   8. While in theory the system need only measure the angle of the    line of sight with respect to horizontal, in practice moving    platforms are rarely aligned with the horizontal plane. So a three    axis inertial measurement system is often used to find the 3 axis    platform altitude and then mathematically combined with the pointing    angles of the camera line of sight, and from that the simple    absolute pitch angle or elevation angle is computed.-   9. MPEG/KLV encoded data can be created from this system and will    retain all information necessary to reconstruct the measurement and    inspection of obstructions.-   10. It is not technically necessary that the optical system contain    an imaging focal plane (like a video camera), since only the optical    centerline matters however in practice they are often used.

The embodiment and examples set forth herein are presented to bestexplain the present invention and its practical application and tothereby enable those skilled in the art to make and utilize theinvention. Those skilled in the art, however, will recognize that theforegoing description and examples have been presented for the purposeof illustration and example only. Other variations and modifications ofthe present invention will be apparent to those skilled in the artfollowing the reading of this disclosure, and it is the intent of theappended claims that such variations and modifications be covered.

The description as set forth is not intended to be exhaustive or tolimit the scope of the invention. Many modifications and variations arepossible in light of the above teaching without departing from the scopeof the following claims. It is contemplated that the use of the presentinvention can involve components having different characteristics. It isintended that the scope of the present invention be defined by theclaims appended hereto, giving full cognizance to equivalents in allrespects.

1. A system comprising: a airborne platform comprising a distancemeasuring module, an altitude measuring module, and an angle measuringmodule wherein the distance measuring module measures a platformdistance from the airborne platform to a target, wherein the altitudemeasuring module measures a platform altitude indicating an altitude ofthe aerial platform, and wherein the angle measuring module measures anelevation angle indicating an angle between horizontal and a line fromthe aerial platform to the target; an analysis module that accepts theplatform distance, the platform altitude, and the elevation angle andcalculates a target height; and a presentation module that presents thetarget height to a user.
 2. The system of claim 1, wherein the airborneplatform further comprises a video camera producing a platform videostream and wherein a synthetic vision module produces a presentationvideo stream related to the platform video stream, wherein thepresentation module accepts the presentation video stream and presents a3 dimensional synthetic presentation and wherein the 3 dimensionalsynthetic presentation comprises a target annotation indicating thetarget height.
 3. The system of claim 1 wherein the airborne platformfurther comprises an optics module comprising a video module and theangle measurement module wherein the video module produces a platformvideo stream and wherein the presentation module presents a presentationbased on a presentation video stream related to the platform videostream and wherein the presentation comprises a height scale reticule.4. The system of claim 3 further comprising a ground communicationsmodule and a camera turret wherein the ground communications modulesends control commands to the airborne platform and wherein the remotecommands direct the camera turret and zoom the video module.
 5. Thesystem of claim 4 further comprising a stabilization system that directsthe camera turret to steady the video module.
 6. The system of claim 1further comprising a stabilization system that directs a camera turretto steady the distance measuring module.
 7. The system of claims 1wherein the distance measuring module is a laser range finder.
 8. Asystem comprising: a airborne platform comprising a distance measuringmodule, an altitude measuring module, a platform location module, and anangle measuring module wherein the distance measuring module measures aplatform distance from the airborne platform to a target, wherein thealtitude measuring module measures a platform altitude indicating analtitude of the aerial platform, wherein the platform locationdetermines a platform location comprising a platform longitude and aplatform latitude, and wherein the angle measuring module measures anelevation angle indicating an angle between horizontal and a line fromthe aerial platform to the target; an analysis module that accepts theplatform distance, the platform altitude, the platform location, and theelevation angle and calculates a target height; and a presentationmodule that presents the target height to a user.
 9. The system of claim8 wherein the analysis module further accepts the platform location andadditionally produces a target coordinate comprising a target latitudeand a target longitude.
 10. The system of claim 9 further comprising adatabase comprising a plurality of obstruction coordinates comprising anobstruction longitude and obstruction latitude and wherein the analysismodule refines the target coordinates based on at least one of theobstruction coordinates.
 11. The system of claim 9 further comprising adatabase and a database updating module wherein the database comprises aplurality of obstruction coordinates comprising an obstruction longitudeand an obstruction latitude and wherein the database updating moduleupdates the obstruction database based on the target coordinate and thetarget height.
 12. The system of claim 8 further comprising a navigationmodule and a database wherein the database comprises a plurality ofobstruction coordinates comprising an obstruction longitude and anobstruction latitude and wherein the navigation module determines aplatform heading from navigation data comprising the platform locationand at least one of the obstruction coordinates.
 13. The system of claim8 further comprising a aiming module and a database wherein the databasecomprises a plurality of obstruction coordinates comprising anobstruction longitude, an obstruction latitude, and an obstructionheight and wherein the aiming module determines a camera aiming vectorfrom aiming data comprising the platform location, platform altitude,and one of the obstruction coordinates.
 14. A system comprising: anairborne platform comprising a distance measuring module, an altitudemeasuring module, an angle measuring module, and a three axis inertialmeasurement system, wherein the distance measuring module measures aplatform distance from the airborne platform to a target, wherein thealtitude measuring module measures a platform altitude indicating analtitude of the aerial platform, wherein the three axis inertialmeasurement system determines the platform attitude, and wherein theangle measuring module measures an elevation angle indicating an anglebetween a platform reference vector and a line from the aerial platformto the target; an analysis module that accepts the platform distance,the platform altitude, the platform attitude, and the platform referencevector and calculates a target height; and a presentation module thatpresents the target height to a user.
 15. A system comprising furthercomprising a platform location module that determines a platformlocation and wherein the analysis module further accepts the platformlocation and additionally produces a target coordinate comprising atarget latitude and a target longitude.
 16. The system of claim 15further comprising a database comprising a plurality of obstructioncoordinates comprising an obstruction longitude and an obstructionlatitude and wherein the analysis module refines the target coordinatesbased on at least one of the obstruction coordinates.
 17. The system ofclaim 15 further comprising a database and a database updating modulewherein the database comprises a plurality of obstruction coordinatescomprising an obstruction longitude and an obstruction latitude andwherein the database updating module updates the obstruction databasebased on the target coordinate and the target height.
 18. The system ofclaim 14 further comprising a navigation module and a database whereinthe database comprises a plurality of obstruction coordinates comprisingan obstruction longitude and an obstruction latitude and wherein thenavigation module determines a platform heading from navigation datacomprising the platform location and at least one of the obstructioncoordinates.
 19. The system of claim 14 further comprising a aimingmodule and a database wherein the database comprises a plurality ofobstruction coordinates comprising an obstruction longitude, anobstruction latitude, and an obstruction height and wherein the aimingmodule determines a camera aiming vector from aiming data comprising theplatform location, platform altitude, and one of the obstructioncoordinates.
 20. The system of claim 19 further comprising a cameraturret and a stabilization system that directs the camera turret tosteady the video module.